Engine governor utilizing plural rate spring



3 Sheets-Sheet l A. W. POPE, JR

ENGINE GOVERNOR UTILIZING PLURAL RATE SPRING March 27, 1956 Filed Aug. 26, 1949 m T N E V N I March 27, 1956 A. w. POPE, JR

ENGINE GOVERNOR UTILIZING PLURAL RATE SPRING 3 Sheets-Sheet 2 Filed Aug. 26, 1949 March 27, 1956 A. W. POPE, JR

ENGINE GOVERNOR UTILIZING PLURAL RATE SPRING 3 Sheets-Sheet 3 Filed Aug. 26, 1949 I N VEN TOR.

7/?774 0/? 14/. POPE, JR.

United States Patent '0 ENGINE GOVERNOR UTILIZING PLURAL RATE SPRING Arthur W. Pope, Jr., Waukesha, Wis., assignor to Waukeslla Motor Company, Waukesha, Wis.

Application August 26, 1949, Serial No. 112,556

8 Claims. (Cl. 264-3) This invention relates to internal combustion engines and more particularly to improved governor means for controlling the amount of fuel supplied to said engines.

Injection type engines, such, for example, as diesel engines, are known to have a relatively flat torque curve, which characteristic is objectionable in the drive of certain types of equipment during the use of which abrupt and substantial increases in load occur. In equipment, such, for example, as agricultural tractors, power shovels, and the like, the engine is normally operated at substantially constant speed under the control of a governor. If an obstruction is encountered, such as hard ground, rocks, stumps, or the like in either plowing by use of a tractor or in the digging operation of a power shovel, the speed of the engine may be reduced below the governed speed range to approximately half speed. If the peak torque of the engine is assumed to be at half speed, the increase of torque of the engine, when dropping from governed speed to half speed is relatively small in view of the fiat characteristic of the torque curve. Thus, an engine operating in this manner has little recovery ability and when the speed is reduced below the governed speed range by a sudden increase in load, it is apt to be stalled or killed.

The output characteristic discussed above with respect to diesel engines is also applicable to carburetor engines,

although in this latter type of engine it is generally possible to' obtain satisfactory torque build-up by altering the volumetric characteristics of the engine which may be accomplished by an-appropriate cam design and restriction of the fuel mixture inlet passages. In certain instances it may be expedient, however, to modify the torque characteristics of a carburetor engine by means other than by altering its volumetric characteristics, and in such instances, a desirable torque output characteristic can be achieved by the use of my improved governor means.

Attempts have heretofore been made to provide governor mechanism for injection type engines to achieve an increase in output torque. when the engine is slowed down under an increased load. The mechanisms heretofore employed for accomplishing this result have utilizedyieldable stop means which permit limited movement of the fuel control lever beyond the position for normal full load operating speed of the engine. The yieldable stop means known in the art are used in lieu of positive stops, usually in the form of stop screws which positively limit the maximum amount of fuel delivered per stroke by the respective pump plungers. It has been found desirable to employ improved governor means whereby the relatively flat output torque curve ofan en-' glue is modified to provide an increase in output torque when the engine is slowed down under an increased load without eliminating the added engine control provided by a positive stop, the position of which is adjustable to determine themaximum amount of fuel delivered to the engine. This result is accomplished as will hereinafter be more fully explained by the use of a novel governor spring, the rate of which is automatically changed when the speed of the engine falls below the controlled engine range.

It is, therefore, an object of my invention to provide an improved and simplified governor control mechanism by which the torque of an associated engine, either injection or carburetor type, is increased to an extent which assures adequate reserve torque when the engine speed is reduced below the governed speed range.

Another object of my invention is to provide an improved governor means for controlling the amount of fuel supplied to an engine when an increased amount of fuel is required to provide an increase in output torque at speeds below the controlled range.

Another object of the invention is to provide an improved governor means for controlling the amount of fuel supplied to an engine which is provided with a single governor spring, the rate of which is changed when the speed of the engine falls below the controlled speed range.

Another object of the invention is to provide an improved governor means which employs a governor spring having means associated therewith by which the effective length of the spring is reduced upon decrease of speed of an engine below normal operating range.

A still further object of my invention is to provide an improved governor means employing a governor spring positioned to urge a control member in a fuel increasing direction and retaining means cooperating with'the spring to prevent a portion of the springfrom exerting force to urge said control member in a fuel increasing direction at engine speeds below the controlled speed range.

Another object of this invention is to provide an im proved governor means which employs a helical spring which may be supported under either tension or compression having means associated therewith by which the efliective force of the spring is reduced upon decrease of speed of an engine below the normal operating range.

A still further object of the invention is to provide an improved governor means for controlling the amount of fuel supplied to an engine which employs a single helical spring, the tension or compression of which is reduced upon the occurrence of a speed decrease below the controlled speed range of the engine.

A still further object of this invention is to provide novel spring structure for biasing a centrifugal type governor.

The invention also resides in certain novel structural characteristics which facilitate the carrying out of the foregoing objects and which contribute both to the simplicity of the governor means and to the ruggedness of construction as well as to the dependability of its opera tion.

Other objects and improvements of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which:

Figure l is a diagrammatic side elevational view of a.

and partly in elevation of the governor biasing spring shown in Figure 1;

Figure 4 is a cross sectional view taken on line 4-4 of Figure 3;

Figure 5 is a perspective view of the stop plate shown gure 1 which is positioned transversely of the helical governor spring intermediate its ends; 1

Figure 6 is an exploded perspective view of the doubly bifurcated yoke and associated parts shown in Figure l; and

Figure 7 is a diagrammatic side elevational view of a fuel injection pump and modified governor means where'- in a compression type governor spring is employed.

While the invention i susceptible of various modifications and alternative constructions, I have shown in the drawings and will herein describe in detail a preferred embodiment, wherein my improved governor means including spring biasing means is utilized for controlling the amount of fuel supplied to an injectiontype engine. It is understood, however, that I do not intend to limit the invention by such disclosure for I aim to cover all modifications and alternative constructions falling Within the spirit and scope of the invention as defined in the appended claims.

Referring to Figure 1, reference numeral 1%) indicates a fuel injection pump which is of known type and a brief description of which will sufiice. prises plungers and barrels in which the plungers are mounted for reciprocation and for turning movement. Each of the barrels is connected by a fuel supply tube 12 to the injection nozzles of an injection type engine (not shown) with which the pump is associated. A control rod 14, which may be in the form of a rack bar, provides means for adjusting the plungers to regulate the amount of fuel delivered per stroke thereby. The pump 10 is also provided with an operating or drive shaft 16,

which has an appropriate driving connection to the drive The shaft of the engine, as is well known in the art. pump 19 is of conventional structure and the construction and operation thereof are well understood in the art, for which reason further description is believed unnecessary.

The terminal end of control rod 14 is pivoted at 18 to one end of a link 20, the other end of which i pivoted at 22 to an operating lever 24 adjacent to the upper end thereof. Operating lever 24 is mounted for pivotal movement about pivot 26 which is positioned adjacent the lower end of lever 24, and pivot 26 is supported on member 28 which may comprise a boss located interiorly of the governor casing identified by reference numeral 36. The operating lever 24 is provided, at its lower end, with a rounded projection 32 disposed for contact by the outer end wall of a sleeve 34 which is slidably mounted on a reduced extension 36 of shaft 16. Sleeve 34 is provided at its inner end with a radially outwardly projecting circumferential flange 38. Thi flange 33 is contacted by the rounded inner ends 40 of inwardly extending arms 42 of bell cranks 44 which are pivoted at 46 on arms 4% that extend radially outward from collar 50 at diametrically opposite sides thereof. Collar St is secured to the reduced extension 36 of shaft 16 by any suitable means, such, for example, as set screw 52, so that the collar 50 and bell cranks 44 will be rotated in unison by shaft 16. The outer arms 54 of bell cranks 44 are provided at their extremities with suitable fly balls or weights 56.

The governor spring as disclosed in Figures 1 and3 comprises a helical spring, identified by reference numeral 58 which is mounted under tension to control the governor mechanism. Attaching means of any suitable type are provided at each end of the spring 58, and in Figures 1 and 3 the attaching means are shown in the form of loops 66 and 68. Loop 66 is inserted in aperture 60 which is positioned in pivoted operating lever 24 intermediate pivot 26 and the free end of the lever. Loop 68, positioned at the opposite end of helical spring 58, is connected to a threaded stud 62 as will hereinafter be more fully explained. In order to mount helical spring 58, threaded stud 62 is adjustably secured to a supporting element which in Figure 1 comprises the governor casing 30. Stud 62 is passed through an opening therein and secured by nut 64 which may be adjusted to vary The pump it) comthe tension of the governor spring. A fuel limit stop screw 25 is threadedly secured in aperture27'forrned in casing 30. The position of the terminal end 29 of the stop screw which engages pivoted lever 24 is adjusted by rotation of the screw, and after adjustment it may be secured in position by tightening locking nut 31. The setting of the terminal end 29 determines the maximum amount of fuel supplied to the engine since the clockwise movement of pivoted arm 24 is terminated upon engagement with the stop screw.

The operating lever 24, and its associated parts ineluding helical spring 58 thus far described, constitute a centrifugal governor wherein the governor spring is supported under tension between aperture 60 and adjustably mounted stud 62. As the speed of rotation of shaft 16 increases with increase in engine speed, the weights or balls 56 move outwardly by centrifugal force, moving the sleeve 34 toward the right. This movement is transferred to pivoted operating lever 24 due to the fact that the end of sleeve 34 is in contact with rounded projection 32 and lever 24 'is moved in a counter-clockwise direction. transferred through pivot 22, linkage 20 and pivot-18 to control rod 14 which causes the rod to move towards the left, which is effective to decrease the amount Of fuel delivered per stroke by the respective plungers of fuel pump 10. As shown in Figure 1, the fly balls or weights 56 are positioned in their outer position, which position they assume as the result of centrifugal force when the engine is operating at substantially full speed. It will be noted that helical spring 58 has been expanded by the movement of operating lever 24 and its spring action is opposed to the outward movement of sleeve 34 resulting from the operation of the fly balls. Thus, under'full speed operating condition, control rod 14 is moved to the left, the entire length of spring 58 is under tension,

and pivoted lever 24 is separated from the terminal end of the stop screw 25. I

When the speed of the engine decreases,the governor spring 58 overcomes the centrifugal force of the' fly balls or Weights 56 and causes the operating lever24. to turn in a clockwise direction, until equilibrium is established. This results in movement of control rod. 14 to the right which increases the amount of fuel de-i livered per stroke. by the respective pump plungers of pump 10. i

The governor assembly is housing or casing 30 whichis mounted in known'manncr,

such, for example, as by bolts 70 on the end of the casing of fuel injectionpump 10.

In the form of. governor spring shown in Figures l and 3, a restriction or abutment is positioued' 'interr mediate the ends of the spring which is indicatediio Figure 3 in the form of stop member or plate 76. This member, which is formed of rigid material, hasa gen erally circular shape, the diameter of which is slightly less than the internal diameter of helical springSSLl' Lug 78 extends from the body portion of the member a distance slightly greater than the diameter of the spring material, and lug extends outwardly an equal dis-. tance from the body portion of the stop member in a diametrically opposite direction from lug 78. Stop'plate 76 is positioned in a plane transverse to the axis of helical spring 58 and intermediate the ends thereof, and lugs 78 and 80 are placed between adjacent convolu-' tions of the spring to maintainthe plate in position. It will be noted that lug 80 is curved in order that plate 76 may be maintained in a substantially transverse plane during flexing of the spring. Stop plate 7.6 is preferably secured in position by a welding tack 82 formed between the outer end of lug '78 and an adjacent convolution -of the spring. Member 76 is provided with a centrally positioned aperture 84 which is generally located. in

alignment with the axis of the helicalspting.

The movement of operating lever 24 is enclosed Within a suitabletends centrally of the helical spring from spring loop 68 to one side of stop plate 76. This extensible member comprises an elongated stud 86 having a terminal portion 88 and a threaded section 90. The terminal portion 88 is slidably contained within aperture 84 of stop plate 76 which serves as a guide to maintain stud 86 in alignment with the axis of the spring and the end of threaded section 90 opposite portion 88 is secured to a yoke 92 which is doubly bifurcated to provide end members 93 that engage and project past spring loop 68. As shown in Figs. 3 and 6, the eye 74 of stud 62 is positioned within one of the slots of yoke 92 and held therein by spring loop 68. This slot is formed with greater depth than the slot formed perpendicularly thereto in which spring loop 68 is cradled.

Internally threaded nut 94 is rotatable upon threaded section 90 to adjust its position longitudinally of the axis of spring 58. An elongated sleeve 96 is positioned between nut 94 and stop plate 76. The sleeve 96 may be formed integrally with nut 94 as a depending skirt or the sleeve may be separate therefrom, although in either form, rotation of nut 94 serves to position the abutting edge 98 of sleeve 96 with respect to stop plate 76. From the description thus far given it will be apparent that sleeve 96, nut 94, elongated stud 86, and doubly bifurcated yoke 92 serve as an extensible rigid member which extends from spring loop 68 to stop plate 76, and by rotation of nut 94 the length of this rigid assembly may be varied.

in order to ascertain the manner in which my improved biasing spring operates in cooperation with the governor and fuel pump to improve the speed-torque curve of an engine, reference is made to Figure 2, wherein two speed-torque curves are presented. The curve a shown in solid lines represents the speed-torque curve of an injection engine to which fuel is delivered by a pump controlled in a conventional manner, and curve 2; shown in a dotted line represents the speed-torque curve of an injection engine utilizing a fuel injection pump controlled by the improved governor biasing spring 58. It is assumed, for purposes of description, that both engines have a controlled speed range of from 1600 R. P. M. to 1760 R. P. M. and operate at the former speed under full load, and that the peak torque of each engine is developed at half speed. The increase in torque below governed speed, as shown by the torque curve a, up to peak torque, is relatively small, as indicated by the vertical distance a between the points 0 and d. The increase in torque up to peak torque, as shown by the torque curve b, which is quite steep and approaches a straight line, is comparatively great, as indicated by the vertical distance b between the points 0 and e. It will be seen that the distance between 0 and e is approximately four times as great as the distance between c and a. Thus, by the employment of the improved governor biasing spring, a substantial increase in torque is obtained upon drop of engine speed below the controlled speed range.

Under normal loading of the engine the speed will be controlled by the governor within the selectedv range in a conventional manner by the movement of control rod 14 to increase the supply of fuel upon decrease of engine speed and to decrease the amount of fuel upon increase of engine speed. The governor spring is adjusted by rotation of nut 64 which varies the position of stud 62 so that all convolutions of the helical spring are under equal tension for each increment of control within the selected speed range.

Modification of the governor spring rate at speeds below the governed speed range is obtained by adjusting nut 94 relative to threaded section 90 of elongated stud 86 so that the abutting edge 98 of sleeve 96 will come into contact with stop plate 76 when the engine is loaded to about 80% of its peak torque. During engine operation at torque output above this value, the abutting edge '98 remains in contact with the stop plate and the convolutions of the spring located between stop plates 76 and loop 68 are prevented from contracting as would, otherwise occur at the decreased speeds if the rigid member was not employed. In effect, the portion of the spring between stop plate 76 and loop 68 is transformed into a rigid body with the spring portion between stop plate 76 and loop 66 remaining resilient and effective to bias the governor and to urge control rod 14 in a fuel increasing direction. It will be apparent from the above discussion that the effective helical length of spring 58 is automatically shortened at speeds below the controlled range and that the length of the rigid member, i. e. sleeve 96, nut 94, stud 86, and yoke 92,

is adjusted by rotation of nut 94 to be greater than the portion of the spring which isspanned when this portion of the spring is in a completely relaxed position. Thus, stop plate 76, sleeve 96, nut 94, stud 86 and yoke 92 serve in the nature of an adjustable retaining means to prevent a portion of the spring from exerting force to urge the control member 14 in a fuel increas-. ing direction at engine speeds below the controlled speed range. When an abrupt overload is placed upon the engine, such, for example, as would occur when the equipment suddenly encounters an obstruction, the en: gine speed drops below the governed speed range. This condition of operation results in the above described modifying action of the governor biasing means since the portion of spring 58 between stop plate 76- and loop 68 is prevented fromcontracting in its normal manner. The resultant change of rate of the governor spring serves automatically to reduce the tendency of control member 14 to move in a fuel increasing direction at engine speeds below the controlling speed range and the resulting torque of the engine is increased as the speed is further decreased until the peak of the torque curve is reached. By changing the governor rate in the zone near the full load range of the engine, a more gradual torque build-up with drop in speed is produced, and a substantial increase in torque, between the controlled speed range and half speed is attained. This modification of the speed-torque characteristic provides for increased recoverability of the engine so that, in the event of a sudden load being imposed upon the engine, due to the equipment encountering an obstruction, the operator has ample opportunity to declutch the mechanism before the engine stalls and may, therefore, overcome the obstacle by proper manipulation of the equipment as is known in the art.

In the modification shown in Figure 7, the effective length and proportionally the effective force of governor spring 58a is automatically reduced upon decrease of engine speed below the normal operating range in order to provide an increase in output torque when the engine is slowed down under an increased load. Spring 58a is mounted in compression to urge pivoted operating lever 24a to rotate in a clockwise direction. to increase the fuel supplied to the motor. With the exception of the spring and parts associated therewith, the governor mechanism shown in Figure 7 is similar to the corresponding mechanism of Figure 1, and the related parts have been indicated by the use of corresponding reference numerals.

Governor spring and positioned between adjustable spring seat 102 and spring plate 104. Stud 100 is threadedly mounted upon casing 38a and extends into the governor chamber Stud 100 may be longitudinally adjusted by rotation of the: aperture 101 and the portion of the stud positioned within the governor casing is provided. reduced section 108. Spring seat 102,

in alignment with pivoted operating lever 24a.

stud in threaded with a threaded is provided with a centrally positioned aperture through which the reduced section passes to permit one side.

of the seat to abut against the shoulder 103 of stud 100. Thus the position of spring seat'102 may be 58a is supported on threaded stud' longitudinally adjusted by rotation of stud 190 and the stud may be secured in adjusted position by locking nut 106. One end of spring 58a is positioned in contact with the opposite side of spring seat 102 and the opposite end of the spring is in engagement with spring plate 104. Operating lever 24a is provided with a pointed projection 110 which rests within the recessed portion located on the opposite side of spring plate 104 as is shown in Figure 7.

Stop plate 76a is positioned and secured by welding tack 82a transverse of the spring axis intermediate the ends thereof. An aperture is provided centrally of the stop plate through which the reduced section 108 of stud 100 freely passes, and nut 112 positioned adjacent to the outer end of stud 100 threadedly engages the threads of reduced section 108 and serves as an abutment for terminating the movement of the stop plate longitudinally of the stud. The stop plate 76a may be formed in a manner similar to the plate shown in Figure 5 or other forms of the plate may be employed which serve to engage an intermediately positioned convolution of the spring. From the description of the mechanism appearing in Figure 7, it will be apparent that stud 100, shoulder 103, spring seat 102, and nut 112 serve as an extensible rigid member, and that a predetermined number of coil convolutions are confined or retained between the spring seat and stop plate of the assembly. The distance between the spring seat and stop plate may be varied by rotation of nut 112 which serves as an adjusting means for determining the limit of movement of stop plate 76:: longitudinally of stud 100.

The governor mechanism shown in Figure 7 serves to control the engine speed under normal loading in a conventional manner to increase the supply of fuel upon decrease of engine speed, and to decrease the amount of fuel supplied to the engine upon increase of the engine speed. The governor spring is adjusted by the adjustment of stud 160 so that all convolutions of the helical spring are under compression for each increment of control within the controlled speed range.

The modification of the governor spring action at speeds below the controlled speed range is obtained by adjusting nut 112, so that the stop plate 76a will come into contact with nut 112 when the engine is loaded to about 80% of its peak torque. During engine operation at torque outputs above this value, stop plate 76:: remains in abutment with nut 112, and the convolutions of the spring positioned between spring seat 102 and stop plate 76a are retained and prevented from expanding as would otherwise occur at the decreased speeds if the afore-described parts were not employed. It will be observed that the portion of the compression spring between spring seat 102 and stop plate 76a is transferred into a rigid body with the spring portion located between the stop plate 760 and spring plate 104 remaining resilient and effective to bias the governor and to urge control rod 14 in a fuel increasing direction.

The occurrence of an abrupt overload upon the engine results in a speed drop of the engine, and as a result of the centrifugal governor action, operating lever 24a is moved in a clockwise direction. The governor spring 58a expands until the portion of the convolutions between spring seat 102 and stop plate 58a are retained against further expansion which results in a modifying action of the effective spring force since only the portion of the spring between stop plate 76a and spring plate 164 remains resilient to urge the operating lever 24a toward a fuel increasing position. This condition of operation serves to reduce the tendency of control member 14 to move in a fuel increasing direction at engine speeds below the controlled speed range and the resulting torque of the engine is thus increased as the speed is further decreased until the peak of the torque curve is reached.

Figure 7 represents the governor parts with the fiy balls or weights 56 positioned in an inner position, which position they assume as the result of centrifugal force when the engine is operating below the controlled speed range. Maximum extent of movement of operating lever 24a is controlled by the position of fuel limit stop screw 25a, and it will be noted that under the operating condition indicated in Figure 7, the pivoted operating member 24a has closely approached the terminal end of fuel limit stop screw 25a.

The engine, either injection or carburetor type, is provided with cylinders and pistons operating therein in a conventional manner. In the operation of the engine, the governor means varies the amount of fuel supplied to the respective engine cylinders per stroke of the respective pistons, as the conditions require, as and for the reasons above stated. In the case of an injection engine, the amount of fuel supplied to the engine per piston stroke is varied by varying the amount of fuel delivered by the pump per stroke of the respective pump plungers. in the case of the carburetor type engine, theamount of fuel supplied to the respective engine cylinders per piston stroke is varied by varying the extent to which the control member or throttle is opened. In either case, i. e. injection engine or carburetor type engine, the amount of fuel supplied to the engine per piston stroke is determined by a fuel supply control member actuated by the governor in cooperation with the biasing spring, and means to modify the tension of the spring as is hereinbefore described.

I claim:

1. Mechanism adapted to control the supply of fuel to an internal combustion engine and comprising a supporting element, a movable control member for regulating the amount of fuel supplied to said engine, a centrifugal governor driven by said engine and operatively connected to move said control member to increase the fuel supply upon decrease of engine speed and to decrease the fuel supply upon increase of engine speed throughout the controlled speed range of said engine, a governor spring having an effective connection between said supporting element and said control member to urge said member in a fuel increasing direction, means to modify the eifect of said spring comprising an abutment positioned intermediate the ends of said spring, and a rigid member comprising a first portion in eiiec'tive engagement with one end of said spring and a second portion positioned to engage said abutment to confine the portion of said spring length between said one end of said spring and said abutment upon the occurrence of a decrease in engine speed below the controlled speed range, said rigid member further comprising coacting threaded sections carried by said first and second portions respectively for adjusting the effective length of the rigid member.

2. Mechanism adapted to control the supply of fuel to an internal combustion engine and comprising a supporting element, a movable control member for regulating the amount of fuel supplied to said engine, a centrifugal governor driven by said engine and operatively connected to move the said control member to increase the fuel supply upon decrease of engine speed and to decrease the fuel supply upon increase of engine speed throughout the controlled speed range of said engine, biasing means for said governor comprising a helical spring supported under tension and having an effective connection between said supporting element and said control member to urge said member in. a fuel increasing direction, means to modify the tension of said springcomprising a stop plate positioned transversely of said spring convolutions and intermediate the ends of said spring, and in extensible rigid member comprising a first portion in effective engagement with the end of said spring and connected to said support- I ing element and a second portion positioned to engage said stop plate to prevent contraction of the portion of the spring length between said end of the spring and said stop plate upon the occurrence of a decrease in speed from the controlled speed range, said extensible rigid member further comprising coacting threaded sections carried by said first and second portions respectively for adjusting the effective length of the rigid member.

3. Mechanism adapted to control the supply of fuel to an internal combustion engine and comprising a supporting element, a movable control member for regulating the amount of fuel supplied to said engine, a centrifugal governor driven by said engine and operatively connected to move the said control member to increase the fuel supply upon decrease of engine spec and to decrease the fuel supply upon increase of engine speed throughout the controlled speed range of said engine, biasing means for said governor comprising a helical spring supported under compression and having an effective connection between said supporting element and said control member to urge said member in a fuel increasing direction, means to modify the compression of said spring comprising a stop plate positioned transversely of said spring convolutions and intermediate the ends of said spring, and an extensible rigid member comprising a first portion in effective engagement with the end of said spring and having said effective connection to said supporting element and a second portion positioned to engage said stop plate to prevent expansion of the portion of the spring length between the said end of the spring and said stop plate upon the occurrence of a decrease in speed from the controlled speed range, said extensible rigid member fur ther comprising coacting threaded sections carried by said first and second portions respectively for adjusting the effective length of the rigid member.

4. Mechanism adapted to control the supply of fuel to an internal combustion engine and comprising a supporting element, a movable control member for regulating the amount of fuel supplied to said engine, a centrifugal governor driven by said engine and operatively connected to move said control member to increase the fuel supply upon decrease of engine speed and to decrease the fuel supply upon increase of engine speed throughout the controlled speed range of said engine, biasing means for said governor comprising a helical spring supported under tension and having an effective connection between said supporting element and said control member to urge said member in a fuel increasing direction, means to modify the tension of said spring comprising a stop plate provided with a centrally located aperture therein, said plate being positioned transversely of said spring convolutions intermediate the ends thereof, an elongated member having an end thereof engaging one end of said spring and the other end slidably positioned in said aperture, and an adjustable means positioned on said elongated memher in abutting relation with said stop plate to prevent the contraction of the portion of said spring length between said one end of the spring and said stop plate upon the occurrence of a decrease in speed from the controlled speed range of the engine.

5. Mechanism adapted to control the supply of fuel to an internal combustion engine and comprising a sup porting element, a movable control member for regulating the amount of fuel supplied to said engine, a centrifugal governor driven by said engine and operatively connected to move said control member to increase the fuel supply upon decrease of engine speed and to decrease the fuel supply upon increase of engine speed throughout the controlled speed range of said engine, biasing means for said governor comprising a helical spring supported under compression and having an effective connection between said supporting element and said control member to urge said member in a. fuel increasing direction, means to modify the compression of said spring comprising a stop plate provided with a centrally located aperture therein,

said plate being positioned transversely of said spring convolutions intermediate the ends thereof, an elongated member serving as a support for a spring seat which engages one end of said spring and an'end of said member slidably positioned in said aperture, and an adjustable means positioned on said elongated member inabutting relation with said stop plate to prevent the expansion of the portion of said spring length between said spring seat and said stop plate upon the occurrence of a decrease in speed from the controlled speed range of the engine.

6. Mechanism adapted to control the supply of fuel to an internal combustion engine and comprising a supporting element, a movable control member for regulating the amount of fuel supplied to said engine, a centrifugal governor driven by said engine and operatively connected to move said control member to increase the fuel supply upon decrease of engine speed and to decrease the fuel supply upon increase of engine speed throughout the controlled speed range of said engine, biasing means for said governor comprising a helical spring supported under tension and having an effective connection between said supporting element and said control member to urge said member in a fuel increasing direction, means to modify the tension of said spring comprising a stop plate provided with a centrally located aperture therein, said plate being positioned transversely of said spring convolutions intermediate the ends thereof, an elongated member having one end thereof engaging one end of said spring and the other end thereof slidably positioned in said aperture, and provided with a threaded portion intermediate its ends, and a nut arranged in threaded engagement with said portion of said elongated member and adapted to be adjusted to abut said stop plate to prevent contraction of the portion of the spring length between said one end thereof and said stop plate upon occurrence of a decrease is speed from the controlled speed range of the engine.

7. An engine governor torque controlling biasing means comprising a helical spring having a plurality of convolutions, a stop plate positioned transversely of said spring convolutions and located intermediate the ends of said spring, and an elongated rigid member positioned axially of said helical spring and having one end thereof engaging an end of said spring, the other end of said member being in abutment with said stop plate when the helical spring is partially expanded and being spaced a distance from said stop plate when said spring is further expanded.

8. An engine governor torque biasing means comprising a helical spring having a plurality of convolutions and provided with attaching means positioned at each end thereof, a stop plate provided with a centrally located aperture therein, positioned transversely of said spring convolutions,.and located intermediate the ends of said spring, an elongated member having an end thereof engaging one end of said spring and the other end slidably positioned in said aperture, and an adjustable means positioned on said elongated member in abutting relation with said stop plate.

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